Many products such as paper products are manufactured from wood chips which are cut from logs that are fed into the cutting station of a chipper. Most large chippers are electrically driven and contain a generally vertically disposed rotatable cutting disc having a series of radially disposed blades equally spaced about the disc. Logs are fed length-wise in a random fashion into the chipping station of the machine by means of a chute and spout assembly where the blades rapidly reduce the logs to chips. As a result, many logs of varying sizes and shapes can be passing through the chute and spout assembly at a given time where it is not uncommon for the logs to become jammed thus terminating the flow of logs into the cutting station.
Because of the extremely high starting loads required by the electrical drive motor of this type of equipment, it is the common practice to clear any log jams without shutting down the machine. It was the early practice in the industry to attempt clearing a jam by manual means using grappling equipment and the like. This method was not only hazardous to the workers who were trying to clear the jam but also to the rotating chipper disc. Grappling equipment that might fall into the chipping station would invariably contact the blades mounted upon the disc and destroy the blades and damage the disc.
Split spouts were later developed as a means of more safely clearing jams in the spout area. The spout in this case includes an enclosed generally cylindrical assembly that is split axially into two approximately half sections. One section is stationarily mounted upon the machine frame while the other section is movably attached to the first section by rocker arms that guide the movable section upwardly and rearwardly away from the cutting station to widen the spout area. The split spout arrangement clearly represents a safety improvement when compared to the more hazardous manual method then employed in the industry. However, the movable section of most split spouts can only separate a few inches from the fixed section of the spout and the device can not be relied upon to clear all log jams that occur in the spout area.
A U.S. Pat. No. 5,477,900 to Gray describes an improved chute and spout assembly that employs a series of hydraulic rams in an effort to clear log jams that might form in the assembly. The rams are spaced about the assembly so that the piston rod of each ram can move upwardly into the log flow stream from a retracted position in the hope that the log or logs causing a jam are dislodged to a point where the flow is reestablished. It has been found, however, that the linearly directed piston rod can oftentimes pass between the logs or produce only a small displacement of the jammed log which is insufficient to clear the jam.